British health experts said the new findings were serious enough to consider
screening IVF patients at regular intervals

Women who undergo IVF are a third more likely to develop ovarian cancer, the biggest ever study of fertility treatment in the world has discovered.

"Most analyses of the dataset suggest that this increased risk was principally because of the nature of women needing these treatments in the first place not due to the hormone drug treatments themselves"

Professor Alastair Sutcliffe, Institute of Child Health at UCL

Scientists at University College London said underlying health problems in infertile women may be driving the increased risk, but warned that the research 'leaves open the possibility' that the procedure itself might be to blame.

Previous studies have suggested that ovarian stimulation methods used to harvest eggs could fuel cancer, but most specialists dispute the dangers and a 2013 Cochrane review found no strong evidence of a link.

However British health experts said the new findings were serious enough to consider screening IVF patients at regular intervals and called for infertile women to be informed that their risk of ovarian cancer was higher than that of women who conceive naturally.

In a groundbreaking study, researchers looked at every IVF procedure recorded by the Human Fertilisation and Embryology Authority (HFEA) which took place in Britain between 1991 and 2010, involving more than 250,000 women.

Presenting the research at a fertility conference in the US, Professor Alastair Sutcliffe from the Institute of Child Health at UCL, said the findings were 'mixed news' for patients.

"Compared to other women in the UK of the same age range and time frame we found the rates of breast and uterine cancer were no different to UK women as a whole. However there was an increased risk of ovarian cancer," he said.

"Most analyses of the dataset suggest that this increased risk was principally because of the nature of women needing these treatments in the first place not due to the hormone drug treatments themselves."

However the findings showed the risk was highest in the first three years after receiving treatment and in younger women.

The authors conclude in their paper: "Certain results argue against an association with assisted reproductive technology itself, but others leave open the possibility that it might affect risk."

Prof Sutcliffe said there was a 'small possibility' that IVF could raise the risk of cancer.

Fertility problems are estimated to affect one in seven heterosexual couples in Britain. Around 50,000 women in the UK undergo 65,000 rounds of IVF or other assisted fertility methods each year.

The risk is still small however. Just 15 in every 10,000 women developed ovarian cancer over the study period, compared with around 11 in 10,000 of the general population.

Ovarian cancer in the UK (1991-2010): Comparing those on IVF with general population

Women on IVF who developed ovarian cancer

Women who developed ovarian cancer

15

11

Sample size: Over 250,000

Professor Geeta Nargund, Medical Director of Create Fertility, which has five clinics in the UK, said that the findings were concerning.

"Not enough has been done to safeguard the health and safety of women undergoing IVF in the UK," she said.

"IVF should be used only when it is really needed. What we do not want is our interventions to put women’s health at risk. We should be moving towards milder stimulation and fewer drugs in IVF.’

“I think it is important that people understand that infertility is not just a cosmetic disease, it is associated with other diseases including ovarian cancer”

Richard Paulson, ASRM vice president

Dr Adam Balen Professor of Reproductive Medicine and Surgery at the University of Leeds, and Chair of The British Fertility Society said the NHS should consider whether women undergoing IVF should be routinely screened for cancer.

"This study, from a huge database, suggests that women who have IVF with certain conditions, such as endometriosis, may be at increased risk of developing ovarian cancer.

"The question remains as to whether women who have received IVF treatment should be offered surveillance/screening and, if so, how often and by what means. I think we need to call for a policy on this."

During IVF, an egg is removed from the woman's ovaries and fertilised with sperm in a laboratory. The fertilised egg is then returned to the woman's womb to grow and develop. However to harvest the eggs the woman is given medication to encourage the body to produce more eggs than usual and those are then collected by inserting a needle into the ovaries.

Women who do not ovulate never get ovarian cancer, and scientists believe that the risk increases with every egg produced. When an ovary produces an egg (ovulation), the surface layer of the ovary bursts to release the egg and must be repaired. The more eggs the ovaries produce the more cells need to divide and the higher the chance that damage will occur that could lead to cancer.

“I think it is important that people understand that infertility is not just a cosmetic disease, it is associated with other diseases including ovarian cancer.”

However charities said that women should not be overly alarmed by the findings.

Dr Julie Sharp, head of health information at Cancer Research UK, said: "This is important research, but doesn't prove fertility treatment increases ovarian cancer risk. As the researchers point out, the risk could be linked to low fertility and related factors.

"The causes of ovarian cancer are complex and we're funding this type of research to give us a better understanding of the most important risk factors, so that we can better advise women thinking about fertility treatment."

The research was presented at the American Society for Reproductive Medicine annual conference in Baltimore.